Optical fiber connector with changeable polarity

ABSTRACT

A multi-fiber, fiber optic connector may include a reversible keying arrangement for determining the orientation for plugging the connector into an adapter to thereby allow for a change in polarity of the connection to be made on site. The connector housing may be configured to engage with a removable key that may be engaged with the housing in at least two different locations to provide the plug-in orientation, or the housing may have slidably displaceable keys movable between multiple positions on the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/707,532 filed on Dec. 9, 2019 which is a continuation of U.S. patentapplication Ser. No. 15/601,308 filed on May 22, 2017, now U.S. Pat. No.10,539,750 issued Jan. 21, 2020, which is a continuation of U.S. patentapplication Ser. No. 14/637,314, filed Mar. 3, 2015, now U.S. Pat. No.9,658,409 issued on May 23, 2017, and all the contents of the abovepatent applications are incorporated by reference in their entirety asif fully set forth herein. The title of the patents above is “OpticalFiber With Changeable Polarity”.

BACKGROUND

Demand for bandwidth by enterprises and individual consumers continuesto experience exponential growth. To meet this demand efficiently andeconomically, data centers have to achieve ultra-high density cablingwith low loss budgets. Fiber optics have become the standard cablingmedium used by data centers to meet the growing needs for data volumeand transmission speeds.

Individual optical fibers are extremely small. For example, even withprotective coatings, optical fibers may be only about 250 microns indiameter (only about 4 times the diameter of a human hair). As such,hundreds of fibers can be installed in cables that will take uprelatively little space. For connections between cables, however, thefibers are terminated with connectors. Multiple fibers may be arrangedwithin a single connector. For example, multi-fiber connectors such asthose using multi-fiber push-on/pull-off (MPO) technology may containand connect 12 or 24 fibers. Connectors, such as MPO type connectors,generally include a housing portion that contains a ferrule thatterminates the ends of the fibers. Ferrules are generally used to retainthe ends of the optical fibers for connecting the optical fibers. Onetype of optical ferrule that may be used with MPO type connectors is anMT (Mechanically Transferable) ferrule.

Typically, MPO connectors are joined together to connect the opticaltransmission path of one fiber optic cable to another fiber optic cableor device, and the connection may be made by inserting the MPOconnectors in an MPO adapter. An adapter generally includes a housing,or portion of a housing, having at least one port which is configured toreceive and hold a connector to facilitate the optical connection of theconnector ferrule with the ferrule of another connector or other device.Adapters may be used to facilitate connections contained within achassis. The term “chassis” as used herein broadly refers to acontainment structure for housing electrical components or switchingcomponents.

As a result of the use of pre-terminated fiber assemblies, the issue ofmaintaining polarity in parallel fiber-optic links is becomingincreasingly important. Described simply, polarity maintains propercontinuity between transmitters and receivers. In order to make surethat connectors are mated correctly with an adapter, the connector andadapter typically include fixed keying features that permit theconnector to be mated with the adapter in generally only one matingconfiguration. While this has the advantage of preventing a connectionthat has the wrong polarity, it also can make it difficult to change thepolarity of the connection on site.

Therefore, there remains a need for multi-fiber, fiber optic connectorsthat have the flexibility of easily changing the polarity of theconnector on site.

SUMMARY

So that the polarity of a multi-fiber, fiber optic connector may bechanged, a housing of the connector may be configured to include aremovable key that may be positioned at alternate locations on thehousing. To change the polarity, the key may be moved from one locationto another.

A multi-fiber fiber optic connector includes a ferrule having aplurality of optical fibers supported therein, and a housing disposedaround at least a portion of the ferrule. The housing has a first endfor being inserted into a fiber optic adapter, a second end disposedopposite the first end, and at least a first wall portion extending fromthe first end towards the second end and a second wall portion oppositethe first wall portion and extending from the first end towards thesecond end, wherein each of the first wall portion and the second wallportion have an internal surface disposed towards the ferrule and anexternal surface disposed outwardly away from the ferrule. The housingdefines a longitudinal axis in a direction from the first end to thesecond end, a transverse axis orthogonal to the longitudinal axis, and avertical centerline through the first and second wall portions. Theconnector also includes a key configured to be removably attached toeither the first wall portion to define a first keyed configuration forinsertion of the first end into the adapter in only a first orientationto define a first polarity with respect to the adapter, or the secondwall portion to define a second keyed configuration for insertion of thefirst end into the adapter in only a second orientation to define asecond polarity with respect to the adapter, wherein the second polarityis opposite to the first polarity. The key includes a first endconfigured for engaging with the housing adjacent the first housing endto prevent movement of the first key end with respect to the housing inat least a direction laterally away from the housing when removablyattached to either the first wall portion or the second wall portion,and a second end disposed longitudinally away from the first end andconfigured for being removably attached to the housing at a secondlocation of the housing spaced longitudinally from the first end of thehousing towards the second end of the housing to prevent movement of thekey with respect to the housing in at least a longitudinal directionalong the housing when removably attached to either the first wallportion or the second wall portion.

In an embodiment, a housing for a fiber optic connector includes a firstend for being inserted into a fiber optic adapter, and a second enddisposed opposite the first end, and the housing defines a longitudinaldirection from the first end to the second end, and a transversedirection orthogonal to the longitudinal direction. The housing alsoincludes at least a first wall portion extending from the first endtowards the second end and a second wall portion opposite the first wallportion and extending from the first end towards the second end, whereineach of the first wall portion and the second wall portion have anexternal surface disposed outwardly away from the ferrule. The housingalso includes a key configured to be removably attached to either thefirst wall portion to define a first keyed configuration for insertionof the first end into the adapter in only a first orientation to definea first configuration with respect to the adapter, or the second wallportion to define a second keyed configuration for insertion of thefirst end into the adapter in only a second orientation to define asecond configuration with respect to the adapter. The key includes oneof a snap-in fastener and a twist lock fastener configured for engagingwith either the first wall portion or the second wall portion, and eachof the first wall portion and the second wall portion comprises anopening configured for receiving the snap-in fastener or the twist infastener to releasably retain the key with either the first wall portionor the second wall portion.

In an embodiment, a method is provided for switching the polarityconfiguration between a multi-fiber fiber optic connector and acorresponding adapter configured for receiving the connector. Theconnector has a connector housing comprising a first end for beinginserted into the adapter, a second end disposed opposite the first end,and at least first and second movably displaceable keys displaceablealong the housing between a first position adjacent the first end and asecond position disposed towards the second end. One of the first andsecond keys may be in its first position and the other of the first andsecond keys may be in its second position to provide a first polarityfor the fiber optic connector. The method includes slidingly displacingthe first key from its corresponding first or second position to theother of the first and second positions, and slidingly displacing thesecond key from its corresponding first or second position to the otherof the first and second positions, to provide a second opposite polarityfor the fiber optic connector.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts perspective views of an MPO connector and adapteraccording to an embodiment.

FIGS. 2A and 2B depict mating/polarity configurations of MPO connectorsaccording to an embodiment.

FIGS. 3A and 3B are representative top and bottom perspective views of afiber optic connector housing with a detachable key for changing thepolarity of the connector according to an embodiment.

FIG. 4 is a perspective view of a partially disassembled fiber opticconnector housing according to the embodiment of FIGS. 3A and 3B.

FIGS. 5A-5D are bottom, top, end and side views of a key according tothe embodiment of FIGS. 3A and 3B.

FIGS. 6A-6E are face, side, cross-sectional and detail views of thefiber optic connector housing according to the embodiment of FIGS. 3Aand 3B.

FIG. 7 is a perspective view of an alternative key according to anembodiment.

FIG. 8 shows the key of FIG. 7 positioned on a connector housingaccording to an embodiment.

FIGS. 9A-9C are face, cross-sectional and detailed views of a connectorof the embodiment of FIG. 8.

FIGS. 10A and 10B are different perspective views of an alternative keyaccording to embodiment.

FIGS. 11A-11C are various views of a connector with the key of FIGS. 10Aand 10B according to an embodiment.

FIGS. 12A and 12B are different perspective views of an alternative keyaccording to an embodiment.

FIGS. 13A-13C are various views of a connector with the key of FIGS. 12Aand 12B according to an embodiment.

FIGS. 14A and 14B are perspective views of a connector with movable keysaccording to an embodiment.

FIGS. 15A and 15B are views of components of the connector of FIGS. 14A,14B with the outer housing removed according to an embodiment.

FIGS. 16A-16C show top, side and cross-sectional views of the connectoror FIG. 14A, 14B according to an embodiment.

FIGS. 17A-17E are various views of the moveable key of FIGS. 14A, 14Baccording to an embodiment.

FIGS. 18A-18D show views of the inner and outer housing components ofthe connector of FIGS. 14A, 14B according to an embodiment.

FIGS. 19A-19E show sequential views (top and cross-sectional) of theprocess of switching the polarity of the connector of FIGS. 14A, 14Baccording to an embodiment.

FIGS. 20A-20C show side and detailed views of the connector of FIGS.14A, 14B according to an embodiment.

FIGS. 21A-21C are views of an alternative movable key according to anembodiment.

FIG. 22 provides a top view of an inner housing for the key of FIGS.21A-21C according to an embodiment.

FIGS. 23A-23C show cross-sectional views of a connector assembly withthe keys of FIGS. 21A-21C according to an embodiment.

FIG. 24 is a perspective view of a connector having a ‘snap-in’ keyaccording to an embodiment.

FIG. 25 is a top view of the inner housing of the connector of FIG. 24according to an embodiment.

FIGS. 26A-26D show bottom, side, end and detailed views of a snap-in keyaccording to an embodiment.

FIG. 27 is a perspective view of an ‘twist-lock’ insertable keyaccording to an embodiment.

FIGS. 28A-28C are bottom, end and side views of the key of FIG. 27according to an embodiment.

FIG. 29 is a top view of the inner housing of a connector for the key ofFIG. 27 according to an embodiment.

FIGS. 30A and 30B show representative views of an internal side of ahousing wall for engaging with the key of FIG. 27 according to anembodiment.

DETAILED DESCRIPTION

As used herein, the term “optical fiber” is intended to apply to alltypes of single mode and multi-mode light waveguides, including one ormore bare optical fibers, coated optical fibers, loose-tube opticalfibers, tight-buffered optical fibers, ribbonized optical fibers, bendperformance optical fibers, bend insensitive optical fibers,nanostructured optical fibers or any other expedient for transmittinglight signals. A multi-fiber optic cable includes a plurality of theoptical fibers. Such cables have a variety of names depending on theirparticular usage, and may be considered as “trunk cables” or “trunks”when connected to fiber optic modules used to form connections to jumpercables using a select polarity.

For connection of cables together or with other fiber optic devices, theterminal ends of a cable may include a connector. A connector mayinclude a housing structure configured to interact with and connect withan adapter. An adapter, in a simple form, may include two aligned portsfor aligning fiber optic connectors therein to align and connect opticalfibers end-to-end. As described herein, the connectors and adapters maybe considered multi-fiber connectors and multi-fiber adapters.

While the following description is directed towards MPO adapters and MPOconnectors with MT optical ferrules, the embodiments described may beapplicable to other adapters, connectors and ferrule types as well. Anembodiment of an MPO connector 10 and adapter 12 are generallyrepresented in FIG. 1. A first end of the connector 10 may include aferrule 14 that may be a multi-fiber ferrule as shown. In addition, theconnector 10 may have attached thereto, a fiber optic cable 15 a andcable boot 15 b (shown only schematically) that may extend from a secondend of the connector.

An adapter 12 may include a first end 16 having a first plug-in port 18for receiving the ferrule end of an optical fiber connector 10 therein,and may include a second end 16 having an additional plug-in port 22(not visible) for receiving an additional MPO optical fiber connector,or other type of fiber optic device therein.

For retention of an MPO connector 10 within each of the ports 18, 22 theports may be provided internally with a connector clip that may beformed by the two resilient tabs 24 a, 24 b configured to bedisplaceable outwardly for insertion and removal of a connector 10 intoor out of the ports 18, 22, and return to essentially their originalposition to engage and retain a connector in the ports. Adapters 12 maybe configured to be mounted on a chassis panel, and may include mountingflanges 26 a, 26 b to mount the adapter via screws, for example.

A connector 10 may include an inner housing 26 that may surround theferrule 14. In the embodiment depicted, ferrule 14 is of the femaletype—a pairing connector may have a male-type ferrule with two guidepins that fit into the receiving holes of the female ferrule. Aconnector 10 may also include an outer housing member 28 that may beslidably disposed about the inner housing 26 adjacent the second end ofthe connector 10. To provide for a pre-determined alignment of the fiberoptic cables within the adapter 12, the inner housing may include analignment key 30 that is configured to fit within keying slot 32 of theadapter. For example, in the embodiment depicted, one of the connector10 or adapter 12 will need to be rotated about its axis 180° to alignthe key 30 with the slot 32. Inner housing 26 may slide into port 18until tabs 24 a, 24 b engage into slots 34 a, 34 b of the inner housing.The outer housing 28 may be moved towards the second end to allow thetabs 24 a, 24 b to engage into slots 34 a, 34 b, and to retain the tabsin the slots, the outer housing may be slid back towards the first endand over the tabs. The outer housing 28 may be biased towards the firstend via springs (shown for example in FIG. 6D) or alternative types ofbiasing devices.

FIGS. 2A and 2B represent the two different modes of connectionalignment to provide for the two different modes of polarity. FIG. 2Amay be indicated as representing what may be termed a ‘normal’ polaritywherein fiber No. 1 of the connector 10 a may mate with fiber No. 1 ofconnector 10 b, and similarly, fiber No. 12 of the connector 10 a maymate with fiber No. 12 of the connector 10 b. For this type ofalignment, the key 30 may be disposed adjacent side A of the ferrule,and the adapter may be keyed accordingly, with the slots 32 (FIG. 1) incorrespondingly opposed surfaces within the adapter 12. To reverse thepolarity of the connection between connectors 10 a, 10 b, as shown inFIG. 2B, the key position of the key 30 of connector 10 b would need tobe changed to the opposite surface for reversed alignment in an adapter12, fiber No. 1 of the connector 10 a may mate with fiber No. 12 ofconnector 10 b, and similarly, fiber No. 12 of the connector 10 a maymate with fiber No. 1 of the connector 10 b. Alternatively, the key 30of the connector 10 a could be changed, or in a further embodiment, adifferent type of adapter may be used, wherein the slots 32 may bealigned on the same internal surface within the adapter 12.

Since an adapter 12 may already be permanently mounted on a surface, andmay have a cable plugged into a back side thereof, an embodiment whereinthe location of key 30 may be changed would provide for a quick, onsitepolarity change. An embodiment of a connector 110 having a detachablekey 130 is represented in FIG. 3. For clarity, the ferrule and any cableand cabling components are omitted. The connector may include an innerhousing 126 and an outer housing 128. The inner housing may have a topside wall 126 a and a bottom side wall 126 b that may be disposedopposite one another, or rotationally, 180° from one another about acentral longitudinal axis 140. The designation top and bottom are usedfor reference only as per the orientation shown, and could alternativelybe interchanged. In an embodiment, each of the side walls 126 a and 126b may be similar, or essentially the same, and each side wall mayinclude a corresponding slot 132 a and 132 b that is configured forreceiving the key 130. At least a portion of the key 130 may beconfigured to be removably insertable into either of the slots 132 a and132 b. The key 130 may be configured in conjunction with the walls 126 aand 126 b to be removably attached with either the top wall 126 a or thebottom wall 126 b. In an embodiment, when key 130 is disposed with thetop wall 126 a, the connector 110 may be configured to define a firstkeyed configuration for insertion of the first end of the connector intoan adapter in only a first orientation to define a first polarity withrespect to the adapter. Alternatively, when key 130 is disposed with thebottom wall 126 b, the connector 110 may be configured to define asecond keyed configuration for insertion of the first end into theadapter in only a second orientation to define a second polarity withrespect to the adapter. As discussed previously, the second polarity maybe considered to be opposite to the first polarity.

FIG. 4 shows a partially disassembled view of the connector 110 of FIGS.3A and 3B. In an embodiment, as shown in greater detail in FIGS. 5A-5D,the key 130 may include a body portion 150 that may include a slot orhole 151 at a first end of the key, and a guide rail 152 at a second endof the key. The guide rail 152 may be configured to fit within either ofthe slots 132 a, 132 b to guide longitudinal movement of the key 130into a slot, and also prevent side-to-side (lateral) movement of the keyonce inserted in the slot. The guide rail 152 and slots 132 a, 132 b mayalso be configured with respect to one another to prevent the key frommoving out of the slot in a direction transverse to the longitudinalaxis. In an embodiment, the width of the slots 132 a, 132 b may widen ina direction from the external surfaces of the housing to the internalsurface. The guide rail 152 may be correspondingly configured, as shownin FIG. 5C to have a narrower width adjacent the body 150 and widen in adirection extending away from the base. With such a configuration thekey 130 may essentially be prevented from being lifted upwardly awayfrom the housing 126 once inserted in a slot 132 a or 132 b, while alsobeing prevented from moving laterally on the housing.

To engage the key 130 longitudinally with respect to the housing 126,the housing may include a projection 160 over which the key body 150 maybe inserted to engage the projection within the hole 151. The projection160 may be tapered outwardly away from the housing in at least theinsertion direction to facilitate movement of the key body 150 up andover the projection. To facilitate removal of a key 130, once engagedwith the projection 160, the key body may include at least one grippingridge 154, or alternatively a plurality of ridges (as shown) disposedalong the body 150. The ridges may be configured to be engaged, forexample with a fingernail, to pull the key from the housing 126.

Additional details of the connector housing 110 may be seen in the viewsrepresented by FIGS. 6A-6F. FIGS. 6A and 6B show representative face andside views of the connector 110 with the key 130 installed. FIG. 6C is across-sectional view along line C-C in FIG. 6A, and FIG. 6D is across-sectional view along line D-D in FIG. 6B. As mentioned previouslywith regard to FIG. 1, the outer housing 128 may be slidably disposedabout the inner housing 126 and a spring 170 may be provided to bias theouter housing forwardly, or towards the first, or insertion end of theinner housing as represented in FIG. 6D. Tabs 129, as shown in detail inFIG. 6E, may be configured to limit forward movement of the outerhousing 128 along the inner housing 126.

The outer housing 128 may be moved rearwardly on the inner housing by adistance d1. Movement of the outer housing over the distance d1 providesaccess to the slots 134 for engagement into the slots of adaptor tabs(such as tabs 24 a, 24 b in FIG. 1) for engagement of the connector 110within an adapter. Similarly, the outer housing 128 may be displaced bythe distance d1 to release the adapter tabs for removal of the connector110 from the adapter. FIG. 6E shows a detailed view of theinterconnection between the key body 150 and hole 151 with theprojection 160 of the inner housing 126. As shown in FIG. 6E, the secondend of the body 150 may fit between the inner housing 126 and outerhousing 128. As such, in an embodiment, the outer housing 128 may bedisplaced by the distance d1 to provide clearance for the key to beinserted onto the inner housing 126. When the outer housing 128 isbiased forwardly as shown, the key body 150 may be prevented from beingreleased from the projection 160. To remove the key 130, the outerhousing 128 may be slid rearwardly by the distance d1 to provideclearance for lifting of the key body 150 outwardly away from around theprojection 160 as shown in FIG. 6F.

An alternative embodiment of a removable key 230 is depicted in FIG. 7.In the embodiment of FIG. 7, the guide rail 252 may essentially besimilar to the guide rail 152 as discussed above. Alternatively, theguide rail 152 may have an alternative configuration. The grippingsurface may include at least one groove 254 that may function inessentially the same manner as the ridges 154 as discussed above, thatis, to provide a surface that may be readily engaged to slide the key230 from the inner housing 226. In an embodiment, the key 230 may have asolid key body 250 at the first end 231, or alternatively, as shown, mayinclude an elongated slot 251 that may provide various functions as setforth further herebelow.

In an embodiment as represented in FIGS. 7 and 8, the configuration forreleasably retaining the key 230 with the inner housing 226 may includelateral tabs 256 a, 256 b at the first, or insertion end 231 of the keybody 250. The lateral tabs 256 a, 256 b may be configured to definecorresponding lateral recesses 258 a, 258 b. The top or bottom surface226, in addition to having slots for receiving the guide rail 252 (notshown, but essentially similar to slots 132 a, 132 b in FIG. 4), mayinclude projections 272 a, 272 b configured to straddle the key body 250wherein the width between the projections may be substantially the sameas the width of the key body between the lateral recesses 258 a, 258 b.

The key 230 may be engaged with the inner housing 226 by insertion ofthe first key end 231 between the projections 272 a, 272 b. By includinga slot 251 between the lateral tabs 256 a, 256 b at the first end 231,the tabs may more easily be deflected inwardly to allow for the tabs topass between the projections 272 a, 272 b. Alternatively, if a slot 251is not included, some polymeric materials of which the key may beconstructed, may be resilient sufficiently to allow for inwardcompression of the tabs 256 a, 256 b to permit the tabs to move past theprojections 272 a, 272 b. Once past the projections 272 a, 272 b, thetabs 256 a, 256 b may again push outwardly and retain the key 230 inengagement with the inner housing 226, at least in the longitudinaldirection of insertion of the key.

The thickness of the body 250 at the first end 231 may essentially bethe same as the space defined between the inner housing 226 and an outerhousing 228 (FIGS. 9A-9C) so that the key 230 cannot be lifted away fromthe inner housing when the outer housing is in place, ensuring thatremoval of the key 230 must be done by longitudinal displacement of thekey from between the projections 272 a, 272 b.

FIGS. 9A-9C show an alternative embodiment of an outer housing 228. Inconjunction with the key 230 having a slot 251, the inside of the outerhousing may include a guide 275 that is configured to fit within theelongated slot for movement within the slot upon movement of the outerhousing longitudinally along the inner housing 226. In an embodiment,the guide 275 could also provide an additional stop for hinderinglongitudinal withdrawal of the key 230 from between the inner housing226 and outer housing 228. When the outer housing 228 is in its forwardbiased position as shown, the thickness of the key body 250 may beessentially the same as the distance between the inner and outerhousings. As such, upon an initial movement of the key 230 in alongitudinally downward in the figure, the slot 251 would move along theguide 275 until the inner surface 231 a of the first end 231 wouldcontact the guide, thereby hindering further outward movement of thekey.

So that the first end 231 of the key 230 may pass into the space betweenthe inner housing 226 and outer housing 228, the inner housing mayinclude a recess 276 that has a depth into the housing that issufficient to permit the first end to pass between the guide 275 and theinner housing. In an embodiment as represented in FIGS. 9B and 9C, thedeepest part of the recess 276 may be located at a position along theinner housing 226 that corresponds to a location at which the guide 275might be located upon displacement of the outer housing 228 towards theback end of the inner housing. As such, when the outer housing 228 isbiased forward into its normal use position, the key 230 will not passbetween the guide 275 and the inner body 226. The key 230 may only passwhen the outer housing 228 is first displaced towards the back end ofthe inner housing 226.

In the various embodiments disclosed herein, the keys and housingcomponents, may be formed of rigid polymers or metals, for example. Ingeneral, any type of substantially rigid material may be used. Thematerial should have a rigidity sufficient to retain the necessaryengagement between the key and the housing so that the key remains inplace except when a force is applied to remove the key.

Another embodiment of a key 330 is shown in FIGS. 10A and 101B. The key330 may, for example, be a formed metal band or rigid polymer. The key330 may include a longitudinal body 350 having a first end 350 a and asecond end 350 b. A connector 310 in conjunction with a key 330 isrepresented in FIGS. 11A-11C. At the front end 327, each of thesidewalls 326 a and 326 b may include a recess or notch 280 that isconfigured to receive the second end of the key 330 therein. The secondend 350 b may be hooked, or U-shaped to provide a bent flange 352configured to fit around the front end 327 of the inner housing 326.Such a configuration of a hook and notch may prevent lateral movement ofthe key 330 on the sidewalls 326 a and 326 b, and may prevent movementtransversely away from the housing, or a lifting off from the housingvia the second end.

The first end 350 a of the key 330 may include a tab 353 that extendssubstantially orthogonally from the body 350. As represented in FIGS.11B and 11C, the inner housing may have a recess, slot or hole 382configured for receiving the tab 353 therein. Once tab 353 is engagedwithin the slot 382, longitudinal movement of the key 330 may beinhibited. As shown in FIG. 11A, outer housing 328 may prevent the firstend 350 a of the key 330 from being lifted away from the inner housing326, so that when the outer housing is biased into its forward position,the key 330 is essentially locked in place on the housing.

Outer housing 328 may be displaced rearwardly for installation andremoval of the key 330. For installation, the outer housing 328 may bedisplaced rearwardly against the bias of springs (not shown, butdiscussed previously). The flange 352 may be aligned with the notch 380and the key may be slid longitudinally into place with the flange in thenotch to align the tab 353 with the slot 382. Tab 353 may be pushed intothe slot 382 and the outer housing 328 may be released to move forwardlyto cover the first end 350 a of the key 330 and hold the key in place.This procedure may be reversed for removal of the key 330. Outer housing328 may be displaced rearwardly, tab 353 may be lifted out of the slot382, and the key may be slid longitudinally off of the inner housing326.

In an alternative embodiment, as represented in FIGS. 12A, 12B and13A-13C, a key 430 may be configured to releasably connect with theouter housing 428. The key 430 may include a longitudinal body portion450 and a guide rail 452 on the second end 450 b. The guide rail 452 maybe configured to engage in a slot 432 a, 432 b of the inner housing 426in a manner as described earlier with regard to FIGS. 6A-6E. In anembodiment, instead of a hole at the insertion end, the body 450 mayinclude a projection 455 that extends away from the body. To engage withthe projection 455, as shown in detail in FIG. 13C, the outer housing428 may include a receptacle 490 into which the projection may extendwhen the outer housing is in place around the inner housing 426.

Similar to earlier embodiments, the second end 450 b of the key 430 maybe retained in the slots 432 a, 432 b in the lateral and transversedirections by the configuration of the guide rail 452. The second end450 b may essentially be movable in only the longitudinal direction uponinsertion or removal of the key 430. When inserted, the first end 450 aof the key 430 may be held in place from lateral movement by a pair ofprojections 492 extending from the inner housing and defining a spacetherebetween that is essentially the same as the width of the bodyportion 450. The outer housing 428 may include depressible tabs 488that, when pressed down, press downwardly on the first end 450 a torelease the projection 455 from engagement in the receptacle 490.

In an alternative embodiment, as shown in FIGS. 14A, 14B, 15A, 15B, 16A,16B and 16C, instead of a single key that may be alternatively placed inconjunction with each face of the top or bottom sidewalls of theconnector, a connector 510 may be configured so that each sidewall 526a, 526 b includes a corresponding displaceable key 530 a, 530 b. Similarto previous embodiments, the connector 510 may include an inner housing526 with a longitudinally displaceable outer housing 528 disposed aboutthe inner housing. Each sidewall 526 a, 526 b may include a longitudinalslot 532 a, 532 b that extends forwardly from the rear end of the innerhousing 526, and as discussed further below, the keys are movablydisposable along the lengths of the slots. Depending on the desiredpolarity, one of the keys 530 a or 530 b may be positioned forwardly inthe slots 532 a, 532 b, while the other is positioned out of the way, orhidden under the outer housing. In an embodiment, the width of the slots532 a, 532 b may widen in a direction from the external surfaces of thehousing to the internal surface.

As shown in FIGS. 17A-17E, each key 530 may include a key body 550 and aprojecting guide rail 552, similar to the key 130 as previouslydiscussed with reference to FIGS. 5A-5D. Projecting rails 552 may have anarrower width adjacent the body 550 and either widen in a directionextending away from the body, or have a base portion disposed away fromthe body that has a width greater than the width adjacent the body.Slots 532 a, 532 b may include an enlarged entry port 533 a, 533 b thathas a width sufficient to allow for passage of the guide rail 552therethrough. FIG. 16B shows the key 530 a disposed over the slot 532 awith the guide rail 552 over the entry port 533 a, and the key 530 bdisposed within the slot 532 b. Once inserted through the entry ports,the keys 530 a, 530 b may be displaceable longitudinally along the slots532 a, 532 b, and once moved forwardly from the entry ports may not belifted out of the slots in a direction transverse to the longitudinaldirection of the slots due to the configuration of the guide rail withthe greater width disposed away from the body.

FIGS. 18A-18D depict the inner housing 526 and outer housing 528. In anembodiment, the inner housing 526 may include stops 529 configured tolimit the forward movement of the outer housing 528 under bias of thesprings 570. The outer housing may have a front end 528 a for beingdisposed towards the front end of the inner housing 526 when disposed onthe inner housing, and a rear end 528 b disposed opposite the front end.The outer housing 528 may include internal stops 561, that may bedisposed adjacent the rear end 528 b, and configured for engaging withthe stops 529 of the inner housing 526. A forward facing surface of thestops 529 may be sloped angularly upwards towards the rear of the innerhousing so that the outer housing can be forced over the stops when theouter housing is slid onto the inner housing from the front end of theinner housing.

FIGS. 19A-19E represent the operation of the displaceable keys 530 a,530 b in relation to the displaceable outer housing 528 and innerhousing 526. FIG. 19A represents a connector configured with a firstpolarity with key 530 a in a forward ‘active’ position and key 530 b ina hidden ‘inactive’ position. To change the polarity, the outer housing528 may be displaced rearwardly on the inner housing 526 as shown inFIG. 19B. After displacing the outer housing 528, key 530 will bepartially exposed. Key 530 a may be slid rearwardly out of its ‘active’position into its ‘inactive’ position and, as shown in FIG. 19C, bothkeys may be in their ‘inactive’ position. Key 530 b may be slidforwardly out of its ‘inactive’ hidden position into its ‘active’position as shown in FIG. 19D, and the outer housing 528 may be releasedto return to its forward position as represented in FIG. 19E.

While the above-described sequence represents one mode of switching thepolarities, the sequence of movements may be altered. For example, key530 b may be moved forwardly prior to moving key 530 a rearwardly. Tohold the keys 530 a, 530 b in the forward, or rearward position, theouter housing and/or keys may include a stop/retention configuration. Inan embodiment as represented in FIGS. 20A-20C, (see also FIG. 18A) theexterior surfaces of walls 526 a, 526 b may include a ridge 563 apositioned corresponding to the forward position of a key, and a ridge563 b positioned corresponding to a rearward position of a key. The keys530 a, 530 b, as represented in FIGS. 17A-17E may include acorresponding slot 565 (FIGS. 17B, 17C, 17E) for engaging with either ofthe ridges 563 a or 563 b depending on the location of the key. Each key530 a, 530 b may therefore be moveable longitudinally over the ridgesand when the slots engage with a ridge, the frictional engagementbetween the keys and the housing will increase and a person working withthe connector will be able to feel when engagement occurs. Once engaged,an additional amount of force would then be needed to move the keys fromtheir engaged positions. Alternative configurations of engagementfeatures may also be provided. As an example, as previously discussedwith reference to FIGS. 7 and 8, lateral projections and recesses,similar to projections 256 a and recesses 258 a may be provided on thesides of a key 530 a, 530 b and the housing surface could include aprojection such as projections 272 a, so that a similar engagement aspreviously described may be provided for positioning of the keys on theinner housing. Alternatively, the features could be reversed wherein thehousing may include slots and the keys may include corresponding ridges.

In a variation of the displaceable key, a key 630 could be configured asdepicted in FIG. 21. In an embodiment, the key 630 may have a longerbody 650 so that more than half of the length of the body, for exampleabout ⅗ to about ⅔ of the key body, will be covered by the outer housing628, as depicted in FIG. 23A, when the outer housing is in its rest, orforward position. With this type of configuration, the guide rail 652may be configured as a ‘fin-like’ projection extending from the body650. As depicted in FIG. 22, a longitudinal slot 632 on the innerhousing 626 may be configured for receipt of the rail 652 therein.Similar to the previously described embodiments, each of the top andbottom surfaces of the inner housing 626 may essentially be identical.

Since at least, for example, about ⅗ of the length of the key 630 may bedisposed between the inner housing and the outer housing, the outerhousing will essentially prevent lateral movement of the key away fromthe inner housing 626 when the outer housing is in its forward positionas represented, for example by key 630 a in FIG. 23A in its forward, or‘active’ position. In this position of the outer housing 628, the key630 b will essentially be hidden in its rearward, or ‘inactive’position. The guide rail 652 may therefore not require any widening atits end away from the body as was previously described for guide rail552.

As in previous embodiments, the outer housing 628 may be displaceablerearwardly to a position as represented in FIG. 23B. In this embodiment,for example, only ⅓ to ⅖ of the ‘active’ key may then be covered by theouter housing. In this position of the outer housing 628 the ‘inactive’key 630 b may be exposed for engaging the key to pull the key forward,if desired. The ‘active’ key 630 a may by pushed rearwardly into its‘inactive’ position, and by changing the position of both keys, thepolarity of the connector may be changed. Alternatively, as representedin FIG. 23C, when the outer housing 628 is in its rearward position, thekeys 630 a and/or 630 b may be removed from the connector or insertedinto position on the connector, as a flexibility of the material of thekey may provide sufficient clearance for the fin 652 to be lifted out ofits corresponding slot 632, so that a key may be pulled form or insertedinto the connector.

In a further embodiment, as represented in FIGS. 24-26C, a connector 710may include a snap-in key 730. Each of top or bottom walls 726 a or 726b of the inner housing 726 may essentially be identical and include aslot 732 for receiving a snap-in projection of the key 730. The key 730may include a key body portion 750 and a projecting engagement member752 that is configured to fit into the slot 732 and retain the key 730in engagement with the inner body 726. The engagement member 752 may beconfigured as a ‘snap-in’ type connector, wherein the engagement membermay compress to fit through the slot 732 and then expand to retainmember within the slot. In general, any type of ‘snap-in’ configurationmay be usable.

In an embodiment as shown, the engagement member 752 may include firstand second leg portions 747 a and 747 b separated by a slot that allowsfor the leg portions to be resiliently displaced towards one another forpassage into and through the slot 732. Once through the slot 732 the legportions 747 a, 747 b may return to their natural position. One or bothof the leg portions 747 a, 747 b may include a catch 749 that projectsoutwardly from the leg portions to give the engagement member a widthwhich is greater than a width of the slot 732. As represented in FIG.26D, with an inner housing wall depicted in outline, when the legportions 747 a, 747 b pass through the slot 732 in the inner housingwall and return to their normal positions, the catches can engage theinside surface of the housing wall to thereby provide a retention forceagainst removing the key 730 from the inner housing 726.

The key body 750 may include recessed notches 745 along the longitudinalsides thereof to facilitate removal of the key 730 from the slot 732.The notches 745 may be configured to provide space for insertion of atool, such as a small screwdriver, or even a fingernail, under the body750 to apply a lifting force and pry the key 730 upwardly away from theinner housing 726. To prevent rotation of a key 730 on the inner housing726, the engagement member 752 and slot 732 may have a length dimension(in a longitudinal direction of the key, or housing) that is at leasttwice as long as a width dimension transverse to the length dimension.

As an alternative to the ‘snap-in’ configuration, as represented inFIGS. 27 and 28A-28C, a key 830 may be configured with a twist-lockconnector 852. The key 830 may include a connector 852 that extends awayfrom the bottom surface of a body portion 850 of the key. The connector852 may include a shaft portion 852 a that extends from the body portion850 and an arm portion 852 b that extends away from the shaft portion.In an embodiment, the arm portion 852 b may extend from the shaftportion 852 a to only one side of the shaft as shown. Alternatively, thearm portion 852 b and shaft portion 852 a may be configured with a “T”configuration and the arm portion may extend bilaterally away from theshaft portion in opposite directions (not shown). The top and bottomwalls 826 a and 826 b may include a corresponding passage 831 having asize and shape configured for passage of the arm portion 826 btherethrough. The shaft portion 852 a may have length extending from thebody portion 850 so that the length may be substantially the same as thethickness of a wall portion of the top and bottom walls 826 a and 826 bat least in the vicinity of the passage 831. The arm portion 852 b, maythereby engage with an inner surface of the top or bottom walls 826 aand 826 b after being inserted through the passage 831 and then rotatedabout the shaft 852 a as represented in FIG. 29.

As shown in FIG. 29, the key 830 may be attached to either of the top orbottom walls 826 a and 826 b by aligning the key as represented by thedashed key outline (longitudinal axis of the key transverse to thelongitudinal axis of the connector), inserting the arm portion 826 bthrough the opening 831 and rotating the key by about 90° to the‘locked-in’ key position as represented by the solid key outline(longitudinal axis of the key aligned with the longitudinal axis of theconnector). Once rotated, the arm portion 826 b as indicated by thedotted outline will no longer be aligned with the passage 831 and willbe engaged with an interior surface of the top or bottom surfaces 826 aand 826 b to thereby prevent a lifting or removal of the key 830 awayfrom the top or bottom walls.

To change the polarity of the connector, the key 830 may be rotated backto its transverse position (dashed line), lifted from the top or bottomwalls 826 a, 826 b, and reinstalled on the opposite surface. To limitrotational movement of the key 830, the interior side of the walls mayinclude a stop member 833, shown in FIG. 30A, which, upon rotation ofthe key about 90°, is engaged by the arm portion 826 b to block furtherrotation. The stop member may be provided by a thickening of the wall, aprojection from the wall, or alternatively, the arm may rotate within adepression 859 extending into the wall from the interior towards theexterior, and which depression may have the shape of a quarter, or halfof a circle, so that the sides of the depression may provide rotationalstops.

In addition to, or as an alternative to the stop 833, in a mannersimilar to the embodiments of FIGS. 18A and 20A, a ridge 863 may beprovided on the exterior surface of the top and bottom walls 826 a and826 b, and the bottom surface of the key body 850 may include acorresponding slot 855 for engaging with the ridge upon rotation of thekey 830 into its locked-in position. The ridge/slot configuration mayalso be configured to provide resistance to minimize inadvertentrotation of a key on the surfaces once a key is ‘lock-in’. If a stop 833is not provided, the ridge/slot configuration would also provide a usera noticeable engagement to indicate a proper alignment of the key on thehousing.

In an alternative embodiment (not shown) the shaft 852 a may be threadedwith at least one circumferential thread and the opening 831 may includea matching thread and rotation of the shaft within the opening maythread the key into and out of the wall in a manner as would berepresented by a nut and bolt engagement.

Various parts, components or configurations described with respect toany one embodiment above may also be adapted to any others of theembodiments provided.

This disclosure is not limited to the particular systems, devices andmethods described, as these may vary. The terminology used in thedescription is for the purpose of describing the particular versions orembodiments only, and is not intended to limit the scope.

In the above detailed description, reference is made to the accompanyingdrawings, which form a part hereof. In the drawings, similar symbolstypically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be used, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds, compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

As used in this document, the singular forms “a,” “an,” and “the”include plural references unless the context clearly dictates otherwise.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. Nothing in this disclosure is to be construed as anadmission that the embodiments described in this disclosure are notentitled to antedate such disclosure by virtue of prior invention. Asused in this document, the term “comprising” means “including, but notlimited to.”

While various compositions, methods, and devices are described in termsof “comprising” various components or steps (interpreted as meaning“including, but not limited to”), the compositions, methods, and devicescan also “consist essentially of” or “consist of” the various componentsand steps, and such terminology should be interpreted as definingessentially closed-member groups.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

Various of the above-disclosed and other features and functions, oralternatives thereof, may be combined into many other different systemsor applications. Various presently unforeseen or unanticipatedalternatives, modifications, variations or improvements therein may besubsequently made by those skilled in the art, each of which is alsointended to be encompassed by the disclosed embodiments.

What is claimed is:
 1. A fiber optic connector comprising: a connectorhousing having a longitudinal axis and comprising an exterior portionextending circumferentially about a space with respect to thelongitudinal axis, the exterior portion including first and secondexterior walls on opposite sides of the longitudinal axis, the connectorhousing being configured to receive a plurality of optical fibers in thespace between the first and second exterior walls, the first exteriorwall comprising a first elongate groove along the longitudinal axis andthe second exterior wall comprising a second elongate groove along thelongitudinal axis; and a polarity change element comprising a keyportion and a tongue, the tongue being configured to be slidablyreceived in a selected one of each of the first elongate groove and thesecond elongate groove to selectively and releasably position thepolarity change element on a corresponding one of the first exteriorwall and the second exterior wall such that the key portion isexternally positioned on the respective one of the first exterior walland the second exterior wall, wherein positioning the polarity changeelement on the first exterior wall such that the key portion isexternally positioned on the first exterior wall configures the fiberoptic connector in a first polarity configuration and positioning thepolarity change element on the second exterior wall such that the keyportion is externally positioned on the second exterior wall configuresthe fiber optic connector in a second polarity configuration; andwherein the fiber optic connector is configured to be plugged into amating receptacle with the connector housing in a first rotationalorientation about the longitudinal axis when the fiber optic connectoris in the first polarity configuration and the fiber optic connector isconfigured to be plugged into the mating receptacle with the connectorhousing in a second rotational orientation about the longitudinal axiswhen the fiber optic connector is in the second polarity configuration,the second rotational orientation being offset from the first rotationalorientation about the axis by 180°; wherein the polarity change elementcomprises opposing lateral tabs defining a first width and the connectorhousing includes a first pair of projections adjacent the first elongategroove and a second pair of projections adjacent the second elongategroove, the first pair of projections separated by a first openinghaving a second width and the second pair of projections separated by asecond opening having the second width, the first width being greaterthan the second width; wherein the fiber optic connector is configuredso that: as the tongue is slidably received in the first elongate grooveto position the polarity change element on the first exterior wall toconfigure the fiber optic connector is in the first polarityconfiguration, the opposing lateral tabs pass through the first openingin a first longitudinal direction, and when the fiber optic connector isin the first polarity configuration, the opposing lateral tabs areconfigured to engage the first pair of projections when the polaritychange element is urged in a second longitudinal direction opposite thefirst longitudinal direction in relation to the connector housing toresist withdrawal of the tongue from the first elongate groove, wherebythe opposing lateral tabs and the second pair of projections releasablyretain the polarity change element on the first exterior wall; andwherein the fiber optic connector is further configured so that: as thetongue is slidably received in the second elongate groove to positionthe polarity change element on the second exterior wall to configure thefiber optic connector is in second first polarity configuration, theopposing lateral tabs pass through the second opening in the firstlongitudinal direction, and when the fiber optic connector is in thesecond polarity configuration, the opposing lateral tabs are configuredto engage the second pair of projections when the polarity changeelement is urged in the second longitudinal direction in relation to theconnector housing to resist withdrawal of the tongue from the firstelongate groove, whereby the opposing lateral tabs and the second pairof projections releasably retain the polarity change element on thesecond exterior wall.
 2. The fiber optic connector as set forth in claim1, wherein each of the first elongate groove and the second elongategroove has an open axial end.
 3. The fiber optic connector as set forthin claim 2, wherein the tongue is configured to be received in each ofthe first elongate groove and the second elongate groove by insertionalong the longitudinal axis into the respective open axial end.
 4. Thefiber optic connector as set forth in claim 3, wherein the connectorhousing comprises a housing front end portion configured to be pluggedinto the receptacle and a housing rear end portion spaced apart from thehousing front end portion along the longitudinal axis in a reardirection, wherein the polarity change element has an element front endportion and an element rear end portion spaced apart from the elementfront end portion in the rear direction.
 5. The fiber optic connector asset forth in claim 4, wherein the element front end portion defines atleast a portion of the key.
 6. The fiber optic connector as set forth inclaim 1, wherein the opposing lateral tabs are spaced apart from atleast a portion of the tongue in the rear direction.
 7. The fiber opticconnector as set forth in claim 1, wherein the connector housingcomprises a housing front end portion configured to be plugged into thereceptacle and a housing rear end portion spaced apart from the housingfront end portion along the longitudinal axis in a rear direction,wherein the polarity change element has an element front end portion andan element rear end portion spaced apart from the element front endportion in the rear direction.
 8. The fiber optic connector as set forthin claim 7, wherein the element front end portion defines at least aportion of the key.
 9. A fiber optic connector comprising: a connectorhousing having a longitudinal axis and comprising an exterior portionextending circumferentially about a space with respect to thelongitudinal axis, the exterior portion including first and secondexterior walls on opposite sides of the longitudinal axis, the connectorhousing being configured to receive a plurality of optical fibers in thespace between the first and second exterior walls, the first exteriorwall comprising a first elongate groove along the longitudinal axis andthe second exterior wall comprising a second elongate groove along thelongitudinal axis; and a polarity change element comprising a keyportion and a tongue, the tongue being configured to be slidablyreceived in a selected one of each of the first elongate groove and thesecond elongate groove to selectively and releasably position thepolarity change element on a corresponding one of the first exteriorwall and the second exterior wall such that the key portion isexternally positioned on the respective one of the first exterior walland the second exterior wall, wherein positioning the polarity changeelement on the first exterior wall such that the key portion isexternally positioned on the first exterior wall configures the fiberoptic connector in a first polarity configuration and positioning thepolarity change element on the second exterior wall such that the keyportion is externally positioned on the second exterior wall configuresthe fiber optic connector in a second polarity configuration; andwherein the fiber optic connector is configured to be plugged into amating receptacle with the connector housing in a first rotationalorientation about the longitudinal axis when the fiber optic connectoris in the first polarity configuration and the fiber optic connector isconfigured to be plugged into the mating receptacle with the connectorhousing in a second rotational orientation about the longitudinal axiswhen the fiber optic connector is in the second polarity configuration,the second rotational orientation being offset from the first rotationalorientation about the axis by 180°; wherein when the fiber opticconnector is in the first polarity configuration, the tongue is receivedin the first elongate groove and the second elongate groove is open; andwherein when the fiber optic connector is in the second polarity thetongue is received in the second elongate groove and the first elongategroove is open.
 10. The fiber optic connector as set forth in claim 9,wherein each of the first elongate groove and the second elongate groovehas an open axial end.
 11. The fiber optic connector as set forth inclaim 10, wherein the tongue is configured to be received in each of thefirst elongate groove and the second elongate groove by insertion alongthe longitudinal axis into the respective open axial end.
 12. The fiberoptic connector as set forth in claim 11, wherein the connector housingcomprises a housing front end portion configured to be plugged into thereceptacle and a housing rear end portion spaced apart from the housingfront end portion along the longitudinal axis in a rear direction,wherein the polarity change element has an element front end portion andan element rear end portion spaced apart from the element front endportion in the rear direction.
 13. The fiber optic connector as setforth in claim 12, wherein the element front end portion defines atleast a portion of the key.
 14. The fiber optic connector as set forthin claim 13, wherein the polarity change element comprises a retainerconfigured to engage the connector housing to releasably retain thepolarity change element on each of the first exterior wall and thesecond exterior wall, the retainer being spaced apart from the elementfront end portion in the rear direction.
 15. The fiber optic connectoras set forth in claim 14, wherein the connector housing comprises aprotrusion on each of the first exterior wall and the second exteriorwall, the retainer being configured to engage the protrusion on each ofthe first exterior wall and the second exterior wall.
 16. The fiberoptic connector as set forth in claim 14, wherein the retainer is spacedapart from at least a portion of the tongue in the rear direction. 17.The fiber optic connector as set forth in claim 12, wherein the polaritychange element comprises a retainer configured to engage the connectorhousing to releasably retain the polarity change element on each of thefirst exterior wall and the second exterior wall, the retainer beingspaced apart from the element front end portion in the rear direction.18. The fiber optic connector as set forth in claim 17, wherein theretainer is spaced apart from at least a portion of the tongue in therear direction.
 19. The fiber optic connector as set forth in claim 9,wherein the connector housing comprises a housing front end portionconfigured to be plugged into the receptacle and a housing rear endportion spaced apart from the housing front end portion along thelongitudinal axis in a rear direction, wherein the polarity changeelement has an element front end portion and an element rear end portionspaced apart from the element front end portion in the rear direction.20. The fiber optic connector as set forth in claim 19, wherein theelement front end portion defines at least a portion of the key.
 21. Thefiber optic connector as set forth in claim 19, wherein the polaritychange element comprises a retainer configured to engage the connectorhousing to releasably retain the polarity change element on each of thefirst exterior wall and the second exterior wall, the retainer beingspaced apart from the element front end portion in the rear direction.22. The fiber optic connector as set forth in claim 21, wherein theconnector housing comprises a protrusion on each of the first exteriorwall and the second exterior wall, the retainer being configured toengage the protrusion on each of the first exterior wall and the secondexterior wall.
 23. The fiber optic connector as set forth in claim 21,wherein the retainer is spaced apart from at least a portion of thetongue in the rear direction.
 24. The fiber optic connector as set forthin claim 21, wherein the polarity change element consists of a singlepiece of material which forms the key portion, the tongue, and theretainer.
 25. The fiber optic connector as set forth in claim 9, whereinthe polarity change element comprises opposing lateral tabs defining afirst width and the connector housing includes a first pair ofprojections adjacent the first elongate groove and a second pair ofprojections adjacent the second elongate groove, the first pair ofprojections separated by a first opening having a second width and thesecond pair of projections separated by a second opening having thesecond width, the first width being greater than the second width. 26.The fiber optic connector as set forth claim 25, wherein the fiber opticconnector is configured so that: as the tongue is slidably received inthe first elongate groove to position the polarity change element on thefirst exterior wall to configure the fiber optic connector is in thefirst polarity configuration, the opposing lateral tabs pass through thefirst opening in a first longitudinal direction, and when the fiberoptic connector is in the first polarity configuration, the opposinglateral tabs are configured to engage the first pair of projections whenthe polarity change element is urged in a second longitudinal directionopposite the first longitudinal direction in relation to the connectorhousing to resist withdrawal of the tongue from the first elongategroove, whereby the opposing lateral tabs and the second pair ofprojections releasably retain the polarity change element on the firstexterior wall; and wherein the fiber optic connector is furtherconfigured so that: as the tongue is slidably received in the secondelongate groove to position the polarity change element on the secondexterior wall to configure the fiber optic connector is in second firstpolarity configuration, the opposing lateral tabs pass through thesecond opening in the first longitudinal direction, and when the fiberoptic connector is in the second polarity configuration, the opposinglateral tabs are configured to engage the second pair of projectionswhen the polarity change element is urged in the second longitudinaldirection in relation to the connector housing to resist withdrawal ofthe tongue from the first elongate groove, whereby the opposing lateraltabs and the second pair of projections releasably retain the polaritychange element on the second exterior wall.